This invention relates to a method of manufacturing a thin film magnetic head and, more particularly, to a method of manufacturing an air flow type thin film magnetic head used for devices such as a fixed-head disk device capable of readily processing various rail patterns on a slider for a thin film magnetic head.
An air flow type magnetic head (in this specification, the term "magnetic head" is used for designating an integral body of a slider and a thin film magnetic head) includes, as shown in FIG. 2A, a slider 12 having rails 14 and 16 on the lower surface (i.e., rail surface) thereof and thin film magnetic heads 18 and 20 provided at the rear end portions of these rails 14 and 16. As shown in FIG. 2B, the magnetic head 10 is lifted away from a rotating magnetic disk 22 on account of a hydrodynamic action caused by the rails 14 and 16 and performs recording and reproducing of information on and from the magnetic disk 22 by the thin film magnetic head 18 or 20 while maintaining a non-contacting state with respect to the magnetic disk 22.
An example of a conventional method of manufacturing the magnetic head 10 shown in FIG. 2A will be described with reference to FIG. 3.
(1) A multiplicity of thin film magnetic heads 22 are formed on a wafer 21 by photolithography or other means.
(2) For preventing chipping which may occur during severing of the wafer 21, vertical and transverse indents 24 and 25 are formed on the wafer 21 at locations selected for forming sliders.
(3) The wafer 21 is severed along the transverse indents 25. Each of the severed pieces of the wafer 21 is called a "row" 26.
(4) One surface of each row 26 is ground and polished to form a rail surface 28. A groove 30 is formed on the rail surface 28 by grinding thereby to form the rails 14 and 16.
(5) Each row 26 is severed along the vertical indents 24 to form a plurality of magnetic heads 10.
The rail surface of a conventional air flow type magnetic head normally has the two parallel rails 14 and 16 as shown in FIG. 2A and FIG. 3. For this reason, in processing the rail surface, as shown in FIG. 4, the rails 14 and 16 are normally formed by forming of the groove by direct machining of the rail surface 28 of the row 26 by means of a rotary blade 32.
The amount of lifting of a magnetic head having such parallel rails from the magnetic disk depends upon the relative speed between the magnetic head and the rotating magnetic disk and normally increases as the relative speed increases. Therefore, there has arisen a demand for a constant amount of lifting of the magnetic head regardless of the relative speed between the magnetic head and the magnetic disk and, as one means for satisfying this demand, there has been proposed a magnetic head 38 as shown in FIG. 5 which has asymmetrical and non-parallel rails 34 and 36.
It is extremely difficult to form such asymmetrical and non-parallel rails 34 and 36 by the machining shown in FIG. 4. The asymmetrical and non-parallel rails have therefore been formed by means of a mask pattern by employing a photo-lithography technique. Such prior art processing of the asymmetrical and non-parallel rails will be described below with reference to FIG. 6.
(1) Rows 26 are formed by severing a substrate on which thin film magnetic heads are formed according to the processings (1) to (3) of FIG. 3. After severing, the rail surface 28 of each row is polished.
(2) A photo-sensitive film 40 is formed by coating a resist or laminating a dry film on the rail surface 28.
(3) A photo-mask 42 provided with asymmetrical and non-parallel rails is disposed on the rows 26 arranged in parallel and then is subjected to light exposure.
(4) By developing, the photo-sensitive film is left in the form of the rail pattern to form mask materials 40'.
(5) The surface of the row 26 in a portion where there is no mask material 40' is etched by ion beam etching.
(6) The mask materials 40' are removed and the row 26 is severed into sliders to form a magnetic head 38 having the asymmetrical and non-parallel rails 34 and 36.
The asymmetrical and non-parallel rails can be formed by the processing shown in FIG. 6 but this processing has the disadvantage that the asymmetrical and non-parallel rails are formed in accordance only with a predetermined rail pattern of the photo-mask 42. Particularly, in a case where two or more thin film magnetic heads are formed on a single magnetic head, and one of the thin film magnetic heads has a better characteristic and a rail pattern to be used differs depending upon which thin film magnetic head is used, a rail pattern formed by means of the photo-mask 42 having a fixed rail pattern results in magnetic heads having a rail pattern different from a pattern to be applied to a thin film magnetic head to be used. Thus, this prior art processing has a very poor production efficiency.
It is, therefore, an object of the present invention to provide a method of manufacturing a thin film magnetic head capable of readily processing various rail patterns.